linux-kernel - [PATCH 2/5] mfd: lm3533-ctrlbank: Cap BRIGHTNESS

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Date:   Mon, 29 Jun 2020 13:32:12 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     lee.jones@...aro.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Johan Hovold <jhovold@...il.com>
Subject: [PATCH 2/5] mfd: lm3533-ctrlbank: Cap BRIGHTNESS_MAX to 127 since API uses u8 as carrier

Since its conception in 2012 brightness has been artificially capped
at 127 since the variable carrying the value is u8.  We could go to
the trouble of changing the whole API (crossing 3 different subsystems),
but clearly this hasn't bothered anyone in the best part of a decade.

Simply, cap BRIGHTNESS_MAX to 127 instead (for now at least).

Fixes the following W=1 warning(s):

 drivers/mfd/lm3533-ctrlbank.c: In function ‘lm3533_ctrlbank_set_brightness’:
 drivers/mfd/lm3533-ctrlbank.c:98:10: warning: comparison is always false due to limited range of data type [-Wtype-limits]
 98 | if (val > LM3533_##_NAME##_MAX) | ^
 drivers/mfd/lm3533-ctrlbank.c:125:1: note: in expansion of macro ‘lm3533_ctrlbank_set’
 125 | lm3533_ctrlbank_set(brightness, BRIGHTNESS);
 | ^~~~~~~~~~~~~~~~~~~

Cc: Johan Hovold <jhovold@...il.com>
Signed-off-by: Lee Jones <lee.jones@...aro.org>
---
 drivers/mfd/lm3533-ctrlbank.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mfd/lm3533-ctrlbank.c b/drivers/mfd/lm3533-ctrlbank.c
index 34fba06ec7057..348ce67453092 100644
--- a/drivers/mfd/lm3533-ctrlbank.c
+++ b/drivers/mfd/lm3533-ctrlbank.c
@@ -17,7 +17,7 @@
 #define LM3533_MAX_CURRENT_MAX		29800
 #define LM3533_MAX_CURRENT_STEP		800
 
-#define LM3533_BRIGHTNESS_MAX		255
+#define LM3533_BRIGHTNESS_MAX		127  /* Capped by API - could be up to 255 */
 #define LM3533_PWM_MAX			0x3f
 
 #define LM3533_REG_PWM_BASE		0x14
-- 
2.25.1